Aeromarine boat



Feb. 10, 1942. T. M. FINLEY 2,272,661

AEROMARINE BOAT Filed Deb. 22, 1938 3 Sheets-Sheet l Feb. 10, 1942. T. M. FINLEY 2,272,661

AEROMARINE BOAT Filed Dec. 22, 1938 3 Sheets-Sheet 2 Feb. 10, 1942. T. M. FINLEY 2,272,661

\ AEROMARINE BOAT Filed D80. 22, 1938 S-Sheets-Sheet 3 Patented Feb. 10, 1942 UNlTED STATES PATENT OFFICE AEROMARINE BOAT Thomas M. Finley, Ironclale, M0. Application December 22, 1938, Serial No. 247,259

(01. iii-66.5)

11 Claims.

The invention relates to an aeromarine boat.

An object of the present invention is to provide an aeromarine boat which with light power and weight will exceed in speed the swiftest of present day crafts and which will approach the speed of the fastest commercial airplanes.

A further object of the invention is to provide an aeromarine boat which at high speed will displace very little water and travel with the major portions of its hull at a few inches altitude with the weight of the boat and its cargo supported almost wholly in the air and at the same time with keels and small portions of the bottom of the hull of the boat in constant contact with the water, thereby assuring not only a very low water resistance but at the same time providing an element of great safety far above that of other speed boats, and at the same time contributing to the directional control of the boat and the maintaining of the same on the desired course.

The further object of the invention is to provide an areomarine boat adapted to utilize both the elements of water and air for its operating media and capable of enabling the proportion of the weight of the boat and its cargo to be supported by the water and the part to be supported by the air when the boat is traveling at high speed to be accurately predetermined and positively controlled by thedesign of the boat.

A further object of the invention is to provide a propeller driven aeromarine boat having a superstructure consisting of an airfoil body or wing provided with a longitudinal opening functioning as a tunnel and laterally tapered in a rearward direction from the front end of the body and providing a flaring entrance to the opening and adapted to accommodate a plurality of propellers spaced apart longitudinally of the body, one in rear of the other, the front end or mouth of the opening being of sufiicient width to enable the front and rear propellers to draw their supply of air from the front end of the boat and from difierent portions of the front end of the same and to cooperate in maintaining a vacuum at the contact end of the body, thereby preventing an air pact from interfering with the forward movement of the body.

Another object of the invention is to terminate the longitudinal opening in a rear slightly tapering substantially circular portion of sufficient diameter to accommodate the slip stream of the propellers for causing the slip stream to discharge or be expelled from the rear end of the opening or tunnel with tremendous rocket thrust force and tend to draw to it air from above the superstructure or airfoil body and from beneath the bottom of the hull of the boat to extend the vacuum above thebody and prevent the air above the vacuum from whipping back and striking the top of the airfoil body between the ends thereof,

and at the same time cause dense air currents to pass beneaththe bottom of the hull of the boat through longitudinal channels and tend to lift and support the boat.

With these and other objects in view, the invention consists in the construction and novel combination and arrangement of parts herein after fully described, illustrated in the accompanying drawings and pointed out in the claims. hereto appended, it being understood that various changes in the form, proportion and details of construction, within the scope of the claims, may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings:

Figure 1 is a perspective View of an aeromarine' boat constructed in accordance with this invention. Fig. 2 is a side'elevation of the same.

Fig. 3 is a plan view of the aeromarine boat, the

arrows indicating the paths of the preslip streams to the front andrear propellers.

Fig. 4 is a longitudinal sectional View taken substantially on the line 4-4 of Fig. 3.

Fig. 5 is a reverse plan View of the aeromarine boat.

Fig. dis. a front elevation of the same.

Fig. 7 is a horizontal sectional View taken substantially on the line 7-1of Fig. 2.

Fig. 8 is a transverse sectional view taken on the line 8-8 of Fig. 2.

Fig. 9 is a similar view taken on the line 9-9 of Fig. 2.

In the accompanying drawings in which is illustrated the preferred embodiment of the invention the aeromarine boat comprises in its" construction a hull l and an upper airfoil super structure or body 2 united or connected with the hull at the top thereof, the bottom of the airfoil body constituting the top or deck of the hull.

The hull and the airfoil body are designed tc be constructed of aluminum or other suitable mate rial and the hull viewed in side elevation isfapproximately cradle shaped and is provided withv a curved bottom 3 which slopes upwardly at each end, as clearly illustrated in Fig. 2 of the drawings. The hull in practice is designed to be pro vided with suitable entrance openings and 'closures and it has curved windows 4' located at the front end of the hull at the top thereof and extending entirely across the same and adapted to afford a clear view both forward and upward. The hull is designed to be provided with other accessories which are omitted for convenience of illustration, and it has central and side longitudinal keel elements 5 and 6 forming central and side channels 1 and 8 which are adapted to trap the air and when the boat moves forward at a high speed are adapted to cause currents of condensed air to pass through the channels from one end of the hull to the other, thereby causing the boat to ride on currents or rails of air, as hereinafter more fully explained. The central laterally spaced keel elements 5 diverge at the front of the hull and form a flaring downwardly tapered entrance to the central main channel for directing the air into the main channel and for causing the same to be compressed therein during its passage through the central channel. The front ends of the side channels are tapered upwardly, as clearly illustrated in Fig. 6 of the drawings, and are adapted to direct the air into the side channels. The keel elements 5 and 6 extend the entire length of the boat from one end of the hull to the other and the central keel elements 5 extend below the plane of the lower edges of the side keel elements and are in the water a greater depththan the side keel elements. In addition, the keel elements act as guards for the bottom of the boat against submerged objects with which th boat might contact.

The bottom of the hull is continuously curved from one end to the other and presents a lower convex surface and the keel elements follow the contour of the curved bottom and have lower curved edges extending longitudinally of th 'bottom of the boat and the air which passes through the channels, as indicated by the arrows in Fig. 4 of the drawings, tend to lift and supportthe boat.

The airfoil body which functions in the nature of an airplane wing is substantially prolate spheroid cross-sectionally and is approximately oblong in plan view, as clearly illustrated in Figs. 3 and 5 of the drawings, and its rear end is provided with lateral extensions 9 which taper forwardly. The airfoil body is provided with a longitudinal opening H], the contour of which is defined by an inner shell ll while the contour of the exterior of the airfoil body is formed by an outer shell I2. The top exterior surface of the airfoil body is curved transversely and presents a transversely convex exterior surface. The lower exterior surfaces I3 of the airfoil body extend laterally beyond the sides of the hull and are curved upwardly, as clearly illustrated in Fig. 6 of the drawings, and they form lower lifting or ground surfaces to enable the airfoil body to function as an airplane wing and for this purpose the airfoil body has a pitch and extends downwardly and rearwardly at an inclination, as clearly illustrated in Fig. 2 of the drawings. While the exterior surfaces'at the top and bottom of the airfoil body are convex to secure the maximum lifting surface and overhead vacuum the prolate spheroid shape of the airfoil body may, of course, be modified with respect to the curvature and lateral inclination of the said surfaces.

The longitudinal opening ID is tapered laterally in .a rearward direction from the front end of the body to a point near the rear end thereof and the rear portion M of the longitudinal opening is circular in cross section and is of a size to accommodate the slip stream of the front and rear propellers l5 and I6, as indicated by the arrows in Fig. 3 of the drawings. The space H between the inner and outer shells of the airfoil body is designed to receive the operating mechanism not shown, for the control of ailerons l8 transversely aligned and hinged at l9 to the rear edges of the airfoil body at the lateral extensions thereof and at opposite sides of the rear end of the longitudinal opening. The said space I! between the inner and outer shells of the airfoil body is designed to receive the operating mechanism of air rudders 20. As the operating mechanism of the ailerons and the air rudders are designed to be of the usual construction for causing the ailerons and air rudders to operate in the usual manner for controlling airships, illustration of such operating mechanism is deemed unnecessary and has been omitted for convenience of illustration.

The front and rear propellers I5 and I6 are mounted on short horizontal shafts 2| and 22 which are journaled in suitable bearings of streamline supports 24 and 25 and which are connected by belt and pulley connections 26 and 21 with front and rear motors 28 and 29 located within the hull of the boat and designed to be mounted in any suitable manner. The motors 28 and 29 are preferably internal combustion engines and while belt and pulleys are preferably employed for transmitting motion from the engines to the propeller shafts, any other suitable means may be employed for this purpose, and the power units are therefore more or less dia grammatically illustrated. The propellers are of regulation air propeller type and while two propellers are illustrated in the accompanying drawings, one or more propellers may be employed and the width of the flaring mouth or entrance of the longitudinal opening of the airfoil will be proportioned with respect to the number of propellers employed so that whether one or more propellers are used, the proper and desired vacuum effect at the front of the airfoil body will be produced. When two propellers are provided, as illustrated in the accompanying drawings, they will be arranged substantially as illustrated in Fig. 3 so that the front propeller will draw the air for its preslip stream from the air in front of the central portion of the front end of the airfoil body while the rear propeller will draw air for its preslip stream at opposite sides of the preslip stream of the front propeller at the spaces between the preslip stream of the front propeller and the side edges of the front end of the tunnel or longitudinal opening Ill.

The aeromarine boat is not a flying machine and is not intended to ride on the air and does not ride on the same out of contact with the water. It utilizes both the elements of water and air for its operating media and portions of the weight of the boat and its cargo are supported by the water and portions by the air. The major air lifting factor lies in the airfoil body which may be so designed and built to support any desired percentage of the weight of the boat and cargo. If to reach the desired speed it is necessary to load three-fourths of the weight of the boat and cargo on the airfoil, the airfoil can be built in such size and at such pitch to support or sustain that proportion of the total weight.

It has been definitely determined by experiments that tunnel airfoils have a very much greater lift per square foot of ground or lower lifting surface than the most efficient airplane wing of the usual construction. The airfoil body which in cross section is substantially prolate spheroid has upper and lower walls forming a longitudinal opening which functions as a tunnel and the upper and lower walls each have inner and outer surfaces and form the tapering longitudinal tunnel opening having the circular rear portion l ljust large enough to accommodate the exit of the slip stream created and impelled by the propellers. located in the tunnel opening. These propellers by virtue of their effect on the air create a vacuum over the entire front surface of the contact end of the airfoil body and entirely along its backwardly tapering interior side surfaces to near the point where the slip stream is expelled. This vacuum space has been estimated to be approximately twenty two per cent more intense or more nearly perfect than that above the wing of an airplane in flight which is estimated to account for approximately eighty per cent of the airplane wings carrying capacity. The vacuum located forwardly of the aeromarine boat has demonstrated repeatedly its great value in adding speed to any vehicle on which it may be used.

t is universally recognized that in tunnel designs it is necessary to supply additional air to all propellers working in rear of the front propeller, otherwise, the rear propellers act only as boosters and while they move very freely they are very ineffective and inefiicient as they operate on a swift stream of air supplied to them by a front propeller, which does all the work of gathering this air and converting it into a slip stream and sending it back to the rear propellers at a high rate of speed. Experiments with such oper ating propellers have shown that so far as thrusts or addition to the speed of the body is concerned the rear propellers without ample additional air furnished them add very little to the speed or forward thrust of the machine. The usual method. used by designers to supply this additional air is by means of passages or slots extending through the body at or near to right angles to the main tunnel of the machine from the outside of its body to the tunnel on the inside of the body. Definite tests of this method disclose that all such transverse passages or slots extending through the body of the machine function fairly well when the body is held captive with the propellers operative but when the body is released and allowed to move forward they begin to lose their efficiency and the faster the movement of the body the less efficient they become almost to the point of extinction. The reason for this is that the slip stream inside the tunnel draws the air from one end of such transverse passages or slots while the swiftly moving body of air outside the body of the machine and across the outer ends of the slots or passages likewise draw the air from the outer ends of such passages or slots which do not operate as conductors of air to the slip stream or propellers but create worthless vacuum pockets.

In the case of the rearwardly tapering longitudinal opening of the present invention the rear propeller operates on the flared front portion of the tunnel as does the front propeller and therefore takes the air which it needs from spaces to the right and to the left of the preslip stream or air which is flowing to the front propeller.

This arrangement enables the rear propeller to have a large part in creating a vacuum at the front end of the tunnel and the higher the speed of the boat; the more perfectly and effectively will be the operation of the rear propeller. It has been, found that in this tapering tunnel the rear motor and propeller often more than doubles the forward thrust of the body. It is estimated that the slip stream expelled from the rear end of the tunnel will have a velocity which will create a tremendous rocket thrust force. The combination of the vacuum at the front end of the boat and the rocket thrust, at the rear end thereof will result in speed developments heretofore unattainable in machines not employing these features. The high velocity slip stream from the point of leaving the rear end of the airfoil body and for some distance back of the boat creates two additional valuable functions or effects, The high velocity slip stream expelled from the rear end of the body has a strong attraction for the surrounding air and adjacent air through which it is moving and exerts a strong attraction for the air immediately above and below the boat. By careful tests repeatedly made it has been found that such a body held at rest, the air over the body and for its length extending from the top of its cambered front end and flowing backwardly to such expelled slip stream has a velocity of approximately threetenths that of the slip stream itself. For example, in one test made with a body forty eight feet and eight inches long and a slip stream flowing at a speed of eighty one miles per hour, the air above the body flowed to the expelled slip stream at the rear at a velocity of twenty four miles per hour and along the top of the body from the highest surface of the cambered front end to within a short distance of the expelled slip stream at the rear of the tunnel. The instrument with which the tests were, made though very sensitive would record the presence of no air movement at the top of the body between the top of the cambered front end and the expelled slip stream at the rear, until elevated some distance above the body of the machine. At a point half way between the top of the cambered end and the expelled slip stream. the instrument showed a space of about fifteen,

inches between the flowing air and the body of the machine. This revealed that the drawing power of the slip stream at the rear overcame.

the natural tendency of the air to whip back and strike the top of the body, which occurs with such displaced air moving above the airplane wings where the allowable cord dimension has been exceeded. The vacuum or rarefied air space above the surface of the body was extended to distances very much greater than the narrow allowable chord for an airplane wing. This is of extreme importance for the reason that much greater efiective square feet of lifting or ground surface may be had with much less overall wing spread. It also insures a more perfect vacuum surface above the airfoil body than is had now in the case of the airplane wing and this will make possible the building of airplanes of much larger ground surface with much less wing spread than is now possible.

The bottom design of the boat is as important to the successful operation and speed of the boat as the airfoil with its vacuum and rocket thrust features. All three features cooperate to produce a unitary result, via, to determine the location of the boat in its operation with relation to the surface of the water and to create the speeds desired. The boat has a tear-drop streamline shape and is much narrower at its rear end than at its front contact end. The bottom of the boat from end to end resembles a rocker being deeper at the center than at either end. As the boat is driven at a high rate of speed it forces the air downward and backward into the three channels that run betweenthe bottom of the boat and the surface of the water. All of these channels extend from end to end of the boat and the principal channel extends down and along the center of the boat while the two side channels or secondary channels are located at the sides of the bottom near the outer walls of the hull. The four keel members 5 and 8 which extend the entire length of the boat, in addition to acting as keels, function as walls or traps to retain and direct the three air currents in the passage of the same beneath the bottom of the boat. The two center walls or keel members extend much deeper into the water than the two outside keel members, the purpose being that if under the influence of a wave or a heavy air roll the boat should tend to leave the water and to take to the air the two outside keel members would leave the water first and this would immediately dissipate two of the air streams that would otherwise assist in lifting the boat. This would reduce the air lift considerably and tend to cause the boat to drop back onto the water. The three streams of air at the longitudinal center and side portions of the bottom of the boat have a much greater density than that of air in its normal state and may properly be termed air-rails and are impelled through the channels between the bottom of the boat and the water by two powerful forces. The first is the speed of the boat which drives the air back int-o these channels. This force alone with the lifting power of the airfoil would be suliicient to insure that the three air currents will be driven clear through the channels beneath the boat, but at the rear end of the boat and in the immediate wake of the boat between the high velocity slip stream and the surface of the water and between the two outside keel members there would be created a powerful vacuum but for the fact that these three streams of air rushing back to it and then on into the slip stream itself. This action or suction at the rear of the boat cooperates with the driving or thrust action at the front end of the boat in causing the three currents of air to pass entirely through the channels from one end of the boat to the other. With the lift of the airfoil relieving the boat of much of what otherwise be water support and the three air streams underneath the boat upon which it moves and the highly effective vacuum at the front of the airfoil body and the powerful rocket thrust at the rear of the body great speeds will be obtained with comparatively low horse power.

The aeromarine boat of the present invention embodies in the front end of the airfoil the apron wing shown and described in my application filed August 5, 1938, Serial No. 223,306, and all of the advantages thereof. Also the prolate spheroid airfoil superstructure of the present invention is another form of the prolate spheroid superstructure shown and described in my application filed February 2, 1938, Serial No. 188,377, now matured into Patent 2,215,919 of September 24, 1940.

The location of the front propeller with relation to the front contact end of the airfoil determines the amount of the additional air supply available for the back propeller.

What is claimed is:

1. An aeromarine propeller driven boat provided at the bottom throughout its entire length with a central unobstructed longitudinal channel and having at the top an airfoil consisting of a single continuous airplane body extending longitudinally of the boat from the bow portion to the stern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being provided with a longitudinal opening extending the entire length of the airfoil with its axis in the vertical median plane of the boat, said opening functioning as a propeller receiving tunnel, and from which a propeller slip stream is expelled with a rocket thrust tending to draw to it air from above the top of the airfoil and from beneath the boat, thereby extending rearwardly the normal vacuum above the front portion of the airfoil and causing air to be drawn from the rear end of the bottom channel and assisting in causing the boat to ride on a stream of air and skim the surface of the water.

2. An aeromarine boat including a hull provided at the bottom throughout its entire length with a central unobstructed longitudinal channel and a top airfoil consisting of a single continuous airplane body extending longitudinally of the boat from the bow portion to the stern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being substantially prolate spheroid in cross section and provided with a longitudinal opening extending the entire length of the airfoil with its axis in the vertical median plane of the boat, said opening functioning as a propeller receiving channel, and a propeller operating in the longitudinal opening, the slip stream of the propeller emerging from the rear end of the opening with a rocket thrust and tending to draw air to it from above and below the boat and increasing the length of the normal vacuum above the front portion of airfoil and causing the air to pass entirely through the bottom channel.

3. An aeromarine boat including a hull provided at the bottom throughout the entire length thereof with smooth unobstructed central and side longitudinal channels having side walls constituting keel elements, and an airfoil consisting of a single continuous airplane body extending longitudinally of the boat from the bow portion to the stern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being approximately prolate spheroid in cross section and provided with a longitudinal opening extending the entire length of the airfoil with its axis in the vertical median plane of the boat, said opening functioning as a propeller receiving tunnel, and a propeller operating in the longitudinal opening, the slip stream of the propeller being expelled from the rear end of the opening with rocket thrust force and tending to draw air to it from above the boat and increasing the length of the normal vacuum above the front portion of the airfoil and also causing the air to pass entirely through the channels beneath the boat.

4. An aeromarine boat including a hull provided at the bottom throughout the entire length thereof with smooth unobstructed central and side longitudinal channels 'having side walls and constituting keel elements at the sides of the central channels and at the sides of the bottom, the keel elements at the sides of the central channel extending to a greater depth than the keel elements at the outer sides of the side channels, and an airfoil consisting of a single continuous airplane body extending longitudinally of the boat from the bow portion to the stern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being substantially prolate spheroid in cross section and provided with a longitudinal opening extending the entire length of the airfoil with its axis in the'vertical median plane of the boat, said opening functioning as a propeller receiving tunnel, and a propeller operatingin the longitudinal opening, the slip stream of the propeller being expelled from the rear end of the opening with a rocket thrust and tending to draw air to it from above and below the boat and increasing the length of the normal vacuum above the front portion of the airfoil and causing the air to pass entirely through the channels beneath the boat.

5. An aeromarine boat including a substantially cradle-shaped hull having its bottom curved longitudinally from one end to the other and presenting a substantially convex lower surface and pro-vided throughout the entire length thereof with a plurality of smooth unobstructed longitudinal channels having walls constituting keel elements and extending from one end of the curved bottom to the other, and an airfoil consisting of a single continuous airplane body extending longitudinally of the boat from the bow portion to the stern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being substantially prolate spheroid in cross section and provided with av longitudinal opening extending the entire length of the airfoil with its axis in the vertical median plane of the boat, said opening functioning as a propeller receiving tunnel, and '2. pr peller operating in the longitudinal opening, the slip stream of the propeller being expelled from the rear end of th opening with a rocket thrust and tending to draw air to it from above and below the boat and increasing the length of the normal vacuum above the front portion of the airfoil and causing the air to pass entirely through the channels.

6. An aeromarine boat including a hull provided at the bottom throughout the entire length thereof with a smooth unobstructed longitudinal channel for the passage of dense currents of air, which tend to lift and support the boat, an airfoil superstructure consisting of a single continuous airplane body extending longitudinally of the boat fromthe bow portion to the stern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being approximately prolate sphero-id in cross section extending substantially the entire length of the hull and having its rear terminal portions laterally extended and tapered forwardly, said superstructure being substantially oblong in plan view and having a single longitudinal opening extending the entire length of the superstructure with its axis in the vertical median plane of the boat and functioning as a propeller receiving tunnel, anda propeller operatingin the longitudinal opening, the slip stream of the propeller being expelled from the rear end of the opening with a rocketthrust and' tending to draw the air to it from the bottom channel and from above the airfoil to the structureand increasing the length of the normal Vacuum above the front portion ofthe same.

'7. An aeromarine boat including a hull provided at the-bottom throughout the entire length thereof with a smooth unobstructed longitudinal channel for the passage of dense currents of air,

which tend to lift and support the boat, and an airfoil superstructure consisting of a single continuous airplane body extending longitudinally of the boat from the bow portion to the'st'ern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being approximately prolate spheroid cross sectienally extending substantially the length of the boat and set at an inclination and provided with a single longitudinal opening extending the entire length of the superstructure with its axis in the vertical median plane of the boat and functioning as a propeller'receiving tunnel, and a propeller operating in the longitudinal opening, the slip stream of the propeller being expelled from the rear endof the opening with a rocket thrust and tending to draw to it from the bottom channel and from above the superstructure and increasing the length of the normal vacuumabove front portion of the said superstructure.

'8. An aeromarine boatincluding a hull-provided at the bottom throughout the entire length thereof with a smooth unobstructedlongitudinal channel for the passage of dense currents of air, which tend to lift and support the boat, and an airfoil superstructure consisting of a single continuous airplane body extending longitudinally of the boat from the bow portion to the stern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being approximately prolate spheroid cross sectionally extending substantially the entire length of the hull and provided with a. single longitudinal opening extending the entire length of the superstructure with its axis in the vertical median plane of the boat and functioning as a propeller receiving tunnel and tapered rearwardly from its front end and having a rear portion circular in cross section, and 'a propeller operating in the longitudinal opening, the rear portion of the opening being of suificient diameter to accommodate the slip stream of the propeller and said slip stream being expelled from the rear end of the opening with a rocket thrust and adapted to displace air from the top of the superstructure and increase the length of the normal vacuum above the front portion of the superstructure said expelled slipstream operating also to draw air through said longitudinal bottom channel.

9. An aeromarine boat including a hull provided at the bottom throughout the entire length thereof with a smooth unobstructed longitudinal channel for the passage of dense currents of air, which tend to lift and support the boat, and an airfoil superstructure consistingof a single continuous airplane body extending longitudinally of the boat from the bow portion to the stern portion thereof and projecting laterally beyond opposite sides of the boat and presenting at each side of the boat a lower lifting surface, said airfoil being approximately prolate spheroid cross sectionally and having a single longitudinal opening extending the entire length of the superstructure with its axis in the vertical median plane of the boat and tapered rearwardly from the front end with top and bottom walls curved transversely, the rear portion of the longitudinal opening being circular in cross section, and spaced propellers operating in the tunnel and arranged to draw air from different portions from the front end of the superstructure to create a vacuum at the leading edge of the airfoil superstructure, said propellers being rotated one in rear of the other and the slip stream of the propellers being expelled from the rear end of the opening with a rocket thrust and tending to draw air to it from the top of the superstructure to increase the length of the normal vacuum space above the front portion of the same said expelled slip stream operating also to draw air through said longitudinal bottom channel.

10. An aeromarine boat including a hull provided at its bottom with a smooth unobstructed longitudinal air channel extending from one end of the hull to the other and arranged to trap air and cause a current of air to pass beneath the hull when the boat is traveling at high speed, an airfoil substantially oblong in plan view and approximately prolate spheroid in cross section and connected along the central portion of its bottom with the hull and presenting at opposite sides of said central bottom portion lifting surfaces extending upwardly and outwardly from the hull whereby when the boat is in motion the air will exert a lifting force against the bottom of the airfoil, said airfoil being provided with a longitudinal opening functioning as a propeller receiving tunnel, and a propeller operating in the longitudinal opening, the slip stream of the propeller being expelled from the rear end of the tunnel with a rocket thrust tending to draw air to it from above the airfoil and. increasing the length of the normal vacuum above the front portion of the airfoil and also arranged to draw to in air from beneath the boat to cause the air to pass entirely through the bottom channel of the hull.

11. An aeromarine propeller driven boat including a substantially cradle-shaped hull having its bottom curved longitudinally from one end to the other and presenting substantially a convex lower surface provided with central and side keel elements forming central and side longitudinal air channels, the central channel being relatively narrow throughout the major portion of its length, and central keel elements having forwardly diverging front portions to provide a flaring entrance to the central channel and the side keel elements being located at the side walls of the hull, the space between the central and side keel elements being relatively wide and the bottom surface of the hull being inclined laterally upwardly and outwardly from the central keel elements to the side keel elements, the central keel elements extending into the water a greater depth than the side keel elements and the front ends of the side air channels being tapered upwardly.

THOMAS M. FINLEY. 

